feat: support focus, colored diffs, error highlights in code blocks (#1534)

Co-authored-by: Divyansh Singh <40380293+brc-dd@users.noreply.github.com>

Author: innocenzi

docs/guide/markdown.md

@@ -71,11 +71,11 @@ For more details, see [Frontmatter](./frontmatter).
 **Input**
 
 ```
-| Tables        | Are           | Cool  |
-| ------------- |:-------------:| -----:|
+| Tables        |      Are      |  Cool |
+| ------------- | :-----------: | ----: |
 | col 3 is      | right-aligned | $1600 |
-| col 2 is      | centered      |   $12 |
-| zebra stripes | are neat      |    $1 |
+| col 2 is      |   centered    |   $12 |
+| zebra stripes |   are neat    |    $1 |
 ```
 
 **Output**
@@ -351,6 +351,131 @@ export default { // Highlighted
 }
 ```
 
+Alternatively, it's possible to highlight directly in the line by using the `// [!code hl]` comment.
+
+**Input**
+
+````
+```js
+export default {
+  data () {
+    return {
+      msg: 'Highlighted!' // [!codeㅤ hl]
+    }
+  }
+}
+```
+````
+
+**Output**
+
+```js
+export default {
+  data () {
+    return {
+      msg: 'Highlighted!' // [!code hl]
+    }
+  }
+}
+```
+
+## Focus in Code Blocks
+
+Adding the `// [!code focus]` comment on a line will focus it and blur the other parts of the code. 
+
+Additionally, you can define a number of lines to focus using `// [!code focus:<lines>]`.
+
+**Input**
+
+````
+```js
+export default {
+  data () {
+    return {
+      msg: 'Focused!' // [!codeㅤ focus]
+    }
+  }
+}
+```
+````
+
+**Output**
+
+```js
+export default {
+  data () {
+    return {
+      msg: 'Focused!' // [!code focus]
+    }
+  }
+}
+```
+
+## Colored diffs in Code Blocks
+
+Adding the `// [!code --]` or `// [!code ++]` comments on a line will create a diff of that line, while keeping the colors of the codeblock. 
+
+**Input**
+
+````
+```js
+export default {
+  data () {
+    return {
+      msg: 'Removed' // [!codeㅤ --]
+      msg: 'Added' // [!codeㅤ ++]
+    }
+  }
+}
+```
+````
+
+**Output**
+
+```js
+export default {
+  data () {
+    return {
+      msg: 'Removed' // [!code --]
+      msg: 'Added' // [!code ++]
+    }
+  }
+}
+```
+
+## Errors and warnings
+
+Adding the `// [!code warning]` or `// [!code error]` comments on a line will color it accordingly.
+
+**Input**
+
+````
+```js
+export default {
+  data () {
+    return {
+      msg: 'Error', // [!codeㅤ error]
+      msg: 'Warning' // [!codeㅤ warning]
+    }
+  }
+}
+```
+````
+
+**Output**
+
+```js
+export default {
+  data () {
+    return {
+      msg: 'Error', // [!code error]
+      msg: 'Warning' // [!code warning]
+    }
+  }
+}
+```
+
+
 ## Line Numbers
 
 You can enable line numbers for each code blocks via config:

package.json

@@ -88,6 +88,7 @@
     "@vueuse/core": "^9.3.0",
     "body-scroll-lock": "4.0.0-beta.0",
     "shiki": "^0.11.1",
+    "shiki-processor": "^0.1.0",
     "vite": "^3.1.6",
     "vue": "^3.2.40"
   },

pnpm-lock.yaml

@@ -329,6 +329,62 @@
   display: inline-block;
 }
 
+.vp-doc [class*='language-'] code .highlighted.error {
+  background-color: var(--vp-code-line-error-color);
+}
+
+.vp-doc [class*='language-'] code .highlighted.warning {
+  background-color: var(--vp-code-line-warning-color);
+}
+
+.vp-doc [class*='language-'] code .diff {
+  transition: background-color 0.5s;
+  margin: 0 -24px;
+  padding: 0 24px;
+  width: calc(100% + 2 * 24px);
+  display: inline-block;
+}
+
+.vp-doc [class*='language-'] code .diff::before {
+  position: absolute;
+  left: 1rem;
+}
+
+.vp-doc [class*='language-'] .has-focused-lines .line:not(.has-focus) {
+  filter: blur(0.095rem);
+  opacity: 0.4;
+  transition: filter 0.35s, opacity 0.35s;
+}
+
+.vp-doc [class*='language-'] .has-focused-lines .line:not(.has-focus) {
+  opacity: 0.7;
+  transition: filter 0.35s, opacity 0.35s;
+}
+
+.vp-doc [class*='language-']:hover .has-focused-lines .line:not(.has-focus) {
+  filter: blur(0);
+  opacity: 1;
+}
+
+.vp-doc [class*='language-'] code .diff.remove {
+  background-color: var(--vp-code-line-diff-remove-color);
+  opacity: 0.7;
+}
+
+.vp-doc [class*='language-'] code .diff.remove::before {
+  content: '-';
+  color: var(--vp-code-line-diff-remove-symbol-color);
+}
+
+.vp-doc [class*='language-'] code .diff.add {
+  background-color: var(--vp-code-line-diff-add-color);
+}
+
+.vp-doc [class*='language-'] code .diff.add::before {
+  content: '+';
+  color: var(--vp-code-line-diff-add-symbol-color);
+}
+
 .vp-doc div[class*='language-'].line-numbers-mode {
   padding-left: 32px;
 }

src/client/theme-default/styles/components/vp-doc.css

@@ -209,6 +209,15 @@
   --vp-code-line-highlight-color: rgba(0, 0, 0, 0.5);
   --vp-code-line-number-color: var(--vp-c-text-dark-3);
 
+  --vp-code-line-diff-add-color: rgba(125, 191, 123, 0.1);
+  --vp-code-line-diff-add-symbol-color: rgba(125, 191, 123, 0.5);
+
+  --vp-code-line-diff-remove-color: rgba(255, 128, 128, 0.05);
+  --vp-code-line-diff-remove-symbol-color: rgba(255, 128, 128, 0.5);
+
+  --vp-code-line-error-color: var(--vp-c-red-dimm-2);
+  --vp-code-line-warning-color: var(--vp-c-yellow-dimm-2);
+
   --vp-code-copy-code-hover-bg: rgba(255, 255, 255, 0.05);
   --vp-code-copy-code-active-text: var(--vp-c-text-dark-2);
 }

src/client/theme-default/styles/vars.css

@@ -1,4 +1,14 @@
-import { IThemeRegistration, getHighlighter, HtmlRendererOptions } from 'shiki'
+import { IThemeRegistration, HtmlRendererOptions } from 'shiki'
+import {
+  createDiffProcessor,
+  createFocusProcessor,
+  createHighlightProcessor,
+  createRangeProcessor,
+  getHighlighter,
+  Processor,
+  addClass,
+  defineProcessor
+} from 'shiki-processor'
 import type { ThemeOptions } from '../markdown'
 
 /**
@@ -32,38 +42,80 @@ const attrsToLines = (attrs: string): HtmlRendererOptions['lineOptions'] => {
   }))
 }
 
+const errorLevelProcessor = defineProcessor({
+  name: 'error-level',
+  handler: createRangeProcessor({
+    error: ['highlighted', 'error'],
+    warning: ['highlighted', 'warning']
+  })
+})
+
 export async function highlight(
   theme: ThemeOptions = 'material-palenight'
 ): Promise<(str: string, lang: string, attrs: string) => string> {
   const hasSingleTheme = typeof theme === 'string' || 'name' in theme
   const getThemeName = (themeValue: IThemeRegistration) =>
     typeof themeValue === 'string' ? themeValue : themeValue.name
 
+  const processors: Processor[] = [
+    createFocusProcessor(),
+    createHighlightProcessor({ hasHighlightClass: 'highlighted' }),
+    createDiffProcessor(),
+    errorLevelProcessor
+  ]
+
   const highlighter = await getHighlighter({
-    themes: hasSingleTheme ? [theme] : [theme.dark, theme.light]
+    themes: hasSingleTheme ? [theme] : [theme.dark, theme.light],
+    processors
   })
-  const preRE = /^<pre.*?>/
+
+  const styleRE = /<pre .* (style=".*")><code>/
+  const preRE = /^<pre(.*?)>/
   const vueRE = /-vue$/
 
   return (str: string, lang: string, attrs: string) => {
     const vPre = vueRE.test(lang) ? '' : 'v-pre'
     lang = lang.replace(vueRE, '').toLowerCase()
 
     const lineOptions = attrsToLines(attrs)
+    const cleanup = (str: string) =>
+      str
+        .replace(preRE, (_, attributes) => `<pre ${vPre}${attributes}>`)
+        .replace(styleRE, (_, style) => _.replace(style, ''))
 
     if (hasSingleTheme) {
-      return highlighter
-        .codeToHtml(str, { lang, lineOptions, theme: getThemeName(theme) })
-        .replace(preRE, `<pre ${vPre}>`)
+      return cleanup(
+        highlighter.codeToHtml(str, {
+          lang,
+          lineOptions,
+          theme: getThemeName(theme)
+        })
+      )
     }
 
-    const dark = highlighter
-      .codeToHtml(str, { lang, lineOptions, theme: getThemeName(theme.dark) })
-      .replace(preRE, `<pre ${vPre} class="vp-code-dark">`)
+    const dark = addClass(
+      cleanup(
+        highlighter.codeToHtml(str, {
+          lang,
+          lineOptions,
+          theme: getThemeName(theme.dark)
+        })
+      ),
+      'vp-code-dark',
+      'pre'
+    )
 
-    const light = highlighter
-      .codeToHtml(str, { lang, lineOptions, theme: getThemeName(theme.light) })
-      .replace(preRE, `<pre ${vPre} class="vp-code-light">`)
+    const light = addClass(
+      cleanup(
+        highlighter.codeToHtml(str, {
+          lang,
+          lineOptions,
+          theme: getThemeName(theme.light)
+        })
+      ),
+      'vp-code-light',
+      'pre'
+    )
 
     return dark + light
   }